Multi-scale research method for improving impurity separation efficiency in ultra-pure metal system

Abstract

The invention discloses a multi-scale research method for improving the separation efficiency of impurities in an ultra-pure metal system. The multi-scale research method comprises the following steps that tellurium crystals are prepared through a zone melting method, and purity and crystal face orientation analysis is conducted; simulation analysis is carried out in combination with experimental data, firstly, phase field simulation is used for analyzing conversion of an interface structure and grain competition-driven orientation in the solidification process, then the density functional theory is used for calculating and analyzing adsorption energy of solid phases on different crystal faces at the solid-liquid interface to impurity atoms, and the structure-activity relationship between crystal face orientation and impurity separation efficiency is obtained. Finally, the crystal face and the preferred orientation degree of the tellurium crystal are regulated and controlled through a Bridgman method, and the impurity separation efficiency is improved. By means of the mode, the key factors influencing trace impurity atom separation can be obtained, the universal method for improving the impurity separation efficiency in the ultra-pure metal system is obtained, and development of the non-ferrous metal metallurgy field is promoted.

Description

Technical Field

[0001] The present invention belongs to the field of nonferrous metal metallurgy, and specifically relates to a multi-scale research method for improving the impurity separation efficiency in an ultra-high purity metal system. Background Art

[0002] Against the backdrop of rapid development in emerging industries, ultra-high-purity dispersed metals with unique physical and chemical properties are of great strategic significance in cutting-edge fields such as electronic information, military applications, and aerospace technology. Against the backdrop of rapid technological advancement, the exponential growth of industrial applications has led to a continuous escalation in the requirements for metal purity. The extremely low yield of purification processes severely limits production efficiency, thereby reducing technical and economic feasibility and directly leading to the high cost of ultra-pure materials. Furthermore, the precise characterization of the location and chemical environment of impurities during separation processes also poses significant scientific and technological obstacles, especially in terms of atomic-level resolution. These limitations collectively constitute a major obstacle to the further development of efficient and deep purification technologies.

[0003] When describing the occurrence state of impurities, four key aspects must be considered: which (impurity element), how much (quantity or concentration), where (location or distribution), and its chemical state (occurrence environment or interaction with the host metal). We rely heavily on high-precision analytical instruments to obtain this data. However, inherent analytical limitations still exist. For example, Sunil Jai Kumar et al. (Talanta, 2016, 159, 14-22) in India measured ultra-low concentrations of impurities in super-8N germanium using inductively coupled plasma mass spectrometry, but were unable to reveal their spatial distribution or occurrence state. Chen Jihua et al. (Journal of Alloys and Compounds, 2022, 906, 164-238) in China observed the distribution of Cu atoms in an alloy system using aberration-corrected transmission electron microscopy, but could only provide limited quantitative analysis. P. Ronsheim et al. (Applied Surface Science, 2008, 255, 1547-1550) in the United States used atom probe tomography to precisely analyze the occurrence state of impurity elements in silicon. However, its limited analytical area limits its ability to reflect the overall purity of the sample. In addition, the analytical limit of this method is not sufficient to achieve high purity levels. In traditional thermodynamic equilibrium phase diagrams, when the solute concentration approaches zero, the boundary between the liquid and solid phases converges, thereby limiting its ability to regulate the separation process in ultra-high purity systems. In addition, some impurity separation theories are mainly derived from low-purity alloy systems and lack an accurate description of the occurrence state and interaction of trace impurities in ultra-pure systems. These limitations hinder the in-depth study of ultra-high purity systems and hinder a comprehensive understanding of the impurity occurrence state and separation behavior.

[0004] It is noteworthy that the microstructure of the solid-liquid interface plays a crucial role in determining impurity distribution and separation behavior. According to classical materials science theory, material properties are essentially determined by structural features from the atomic to the macroscopic scale. However, most impurity separation research focuses on macroscopic results, and the mechanisms by which microstructure affects impurity migration are still unclear. In particular, systematic studies of atomic-scale impurity behavior remain rare. Therefore, establishing the relationship between microstructure and separation efficiency is expected to provide a new research paradigm for the precise removal of impurities in ultra-high-purity metals. Summary of the Invention

[0005] The purpose of the present invention is to address the above-mentioned problems and provide a multi-scale research method to improve the impurity separation efficiency in ultra-high purity metal systems, to provide a multi-scale explanation of the impurity separation mechanism in the regional refining process, to clarify the mechanism of selective impurity separation at the interface and to establish a "structure-performance" relationship, thereby improving the impurity separation efficiency by regulating the crystal plane and the degree of preferred orientation.

[0006] Based on the above objectives, the present invention adopts the following technical solutions:

[0007] S1. Prepare tellurium crystals by zone melting, analyze their purity and crystal orientation, and obtain experimental data.

[0008] S2. Use phase field simulation to analyze the interface structure and grain competition-driven orientation changes during solidification to obtain macroscopic theoretical data;

[0009] S3. Use density functional theory to calculate and analyze the adsorption energy of impurity atoms on different crystal planes at the solid-liquid interface, obtain the structure-activity relationship between crystal plane orientation and impurity separation efficiency, and obtain microscopic theoretical data;

[0010] S4. The crystal plane and preferred orientation degree of the tellurium crystal are regulated by the Bridgman method to obtain an optimized solution.

[0011] Furthermore, in step S1, the zone melting method is as follows: the tellurium raw material is placed in a quartz boat, which is then loaded into the quartz tube of a zone purification device. High-purity inert gas is continuously introduced to purge the air in the quartz tube. As the heating coil operates, the melting zone moves from the head to the tail of the sample. The purification process is completed at a set melting rate, and the tellurium in the middle portion is collected. In step S2, a multiphase field model is used to simulate the interface evolution during the zone melting process. In step S3, calculations are performed using the DMOL3 software package based on density functional theory (DFT).

[0012] Furthermore, the purity of the raw tellurium is 5-6N; the size of the quartz boat is 550mm×50mm×50mm; the inert gas is argon; the melting rate is 25, 50, 75, 100mm h -1 .

[0013] Furthermore, in step S1, the purity analysis method of the tellurium crystal is inductively coupled plasma mass spectrometry, and the crystal plane orientation analysis method is X-ray diffraction.

[0014] Furthermore, in step S2, the phase field simulation uses a tellurium system containing tin and bismuth impurities to simulate the competitive growth of dendrites on crystal planes such as (001), (011), (012), (104) and (101) as the melting rate changes.

[0015] Furthermore, in step S3, the theoretical calculation is specifically the adsorption energy of impurity atoms at the solid-liquid interface of the (104), (101) and (012) crystal planes; the structure-activity relationship is that the lower the adsorption energy value, the lower the impurity separation efficiency.

[0016] Furthermore, in step S4, the Bridgman method for controlling the crystal plane and preferred orientation of the tellurium crystal is as follows: the tellurium crystal is grown in a Bridgman crystal growth furnace. A tellurium-containing growth crucible is evacuated and encapsulated with a hydroxide flame, and the heated zone is adjusted to grow the tellurium crystal. The tellurium crystal is cut along a specific crystal plane using a diamond wire saw and placed in a seeding well in the crucible to induce growth of a specific preferred crystal plane.

[0017] Furthermore, the vacuum degree of the crucible is 1×10 -5 -4×10 -5 The growth temperature of the Bridgman crystal growth furnace is 450-460 ℃, and the temperature gradient is 10-15 ℃ cm -1 , with a growth rate of 1-1.5 mm h -1 ; The specific crystal planes are (012), (104) and (101); the purpose of the regulation is to enhance the degree of preferential orientation of the crystal planes.

[0018] Furthermore, the metal samples in steps S1-S4 can be replaced by germanium, selenium, indium, antimony, rhenium, thallium, etc., and the method is universal.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] This paper uses tellurium as a prototype to provide a multi-scale explanation of the impurity separation mechanism during the zone refining process. Experimentally, the control of the fusion rate on the evolution of the microstructure was systematically studied. Phase field simulation revealed the dynamic mechanism of different orientation competition driven by interface structure and grain competition. Density functional theory calculations quantified the adsorption energy differences of different crystal planes at the atomic scale, clarifying the mechanism of selective impurity separation at the interface. A multi-scale modeling method was proposed to establish a "structure-performance" relationship, and the Bridgman method was used to regulate the crystal plane and the degree of preferred orientation to enhance the impurity separation efficiency. The different dependencies of the impurity existence state on the microstructure can be used for intelligent purification with high economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is an analysis chart of the impurity content of tellurium crystals prepared at different melting rates;

[0022] Figure 2 is the XRD pattern of tellurium crystals prepared at different melting rates;

[0023] Figure 3 is at 100mm h -1 HRTEM images of tellurium crystals prepared at melting rates;

[0024] Figure 4 These are optical microscope photos of tellurium crystals prepared at different melting rates;

[0025] Figure 5 It is a dendrite competition growth model of the (012) and (011) crystal planes of tellurium crystal;

[0026] Figure 6 is the adsorption energy diagram of impurity atoms at the solid-liquid interface between the (104) and (012) crystal planes of tellurium crystal;

[0027] Figure 7 The XRD patterns of (104) and (012) crystal plane samples grown using the Bridgman method are shown in Figure 2.

[0028] Figure 8 This is an analysis chart of the impurity content of (104) and (012) crystal plane samples grown using the Bridgman method. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings to make the advantages and features of the present invention more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the scope of protection of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without inventiveness are also within the scope of protection of the present invention.

[0030] Example 1

[0031] The present invention provides a multi-scale research method for improving the impurity separation efficiency in an ultra-high purity metal system, comprising the following steps:

[0032] S1. Prepare tellurium crystals by zone melting and analyze their purity and crystal orientation.

[0033] The 5N grade tellurium raw material was placed in a quartz boat (550 mm × 50 mm × 50 mm), and then loaded into the quartz tube of the partition purification device. High-purity argon gas was continuously introduced to purge the air in the quartz tube. As the heating coil was running, the melting area moved from the head to the tail of the sample. The melting rates were 25 and 100 mm h -1 The purity of the sample was determined by inductively coupled plasma mass spectrometry, and the crystal orientations of the sample were (104) and (012) by X-ray diffraction analysis.

[0034] S2. Analyze the interface structure and grain competition-driven orientation changes during solidification using phase-field simulation.

[0035] Phase-field simulation was conducted using a tellurium system containing tin and bismuth impurities to simulate the competitive growth of dendrites on the (001), (011), (101), (104) and (012) planes as the melting rate varied. It was found that at high melting rates, the (012) plane showed preferential growth.

[0036] S3. Density functional theory is used to calculate and analyze the adsorption energy of impurity atoms on different crystal planes at the solid-liquid interface to obtain the structure-activity relationship between crystal plane orientation and impurity separation efficiency;

[0037] Density functional theory was used to calculate and analyze the adsorption energies of impurity atoms at the solid-liquid interface on the (104) and (012) crystal planes. It was found that the adsorption energy of the (012) crystal plane on all impurity atoms in the system was higher than that on the (104) crystal plane, which means that impurity atoms are more easily separated from the (012) crystal plane to the liquid phase, which is beneficial to improving the impurity separation efficiency.

[0038] S4. The crystal plane and preferred orientation degree of tellurium crystals are regulated by the Bridgman method.

[0039] Tellurium crystal growth is carried out in a Bridgman crystal growth furnace. The tellurium-containing growth crucible is evacuated to a vacuum degree of 4×10 -5 Pa, and enclose the growth crucible with hydroxide flame; adjust the heating zone to grow tellurium crystals, the growth temperature is 460℃, and the temperature gradient is 10℃cm -1 , the growth rate is 1 mm h -1Tellurium crystals were cut along the (012) crystal plane using a diamond wire saw and placed in the seed crystal slot of the crucible to induce the growth of specific preferential crystal planes, thereby increasing the orientation of the (012) crystal plane and improving the impurity separation efficiency.

[0040] Example 2

[0041] The present invention provides a multi-scale research method for improving the impurity separation efficiency in ultra-high purity metal systems. The difference from Example 1 is that the melting rate is changed to 50 and 100 mm h -1 , including the following steps:

[0042] S1. Prepare tellurium crystals by zone melting and analyze their purity and crystal orientation.

[0043] The 5N grade tellurium raw material was placed in a quartz boat (550 mm × 50 mm × 50 mm), and then loaded into the quartz tube of the partition purification device. High-purity argon gas was continuously introduced to purge the air in the quartz tube. As the heating coil was running, the melting area moved from the head to the tail of the sample. The melting rates were 50 and 100 mm h -1 The purity of the sample was determined by inductively coupled plasma mass spectrometry, and the crystal orientations of the sample were (104) and (012) by X-ray diffraction analysis.

[0044] S2. Analyze the interface structure and grain competition-driven orientation changes during solidification using phase-field simulation.

[0045] Phase-field simulation was conducted using a tellurium system containing tin and bismuth impurities to simulate the competitive growth of dendrites on the (001), (011), (101), (104) and (012) planes as the melting rate varied. It was found that at high melting rates, the (012) plane showed preferential growth.

[0046] S3. Density functional theory is used to calculate and analyze the adsorption energy of impurity atoms on different crystal planes at the solid-liquid interface to obtain the structure-activity relationship between crystal plane orientation and impurity separation efficiency;

[0047] Density functional theory was used to calculate and analyze the adsorption energies of impurity atoms at the solid-liquid interface on the (104) and (012) crystal planes. It was found that the adsorption energy of the (012) crystal plane on all impurity atoms in the system was higher than that on the (104) crystal plane, which means that impurity atoms are more easily separated from the (012) crystal plane to the liquid phase, which is beneficial to improving the impurity separation efficiency.

[0048] S4. The crystal plane and preferred orientation degree of tellurium crystals are regulated by the Bridgman method.

[0049] Tellurium crystal growth is carried out in a Bridgman crystal growth furnace. The tellurium-containing growth crucible is evacuated to a vacuum degree of 4×10 -5Pa, and enclose the growth crucible with hydroxide flame; adjust the heating zone to grow tellurium crystals, the growth temperature is 460℃, and the temperature gradient is 10℃cm -1 , the growth rate is 1 mm h -1 Tellurium crystals were cut along the (012) crystal plane using a diamond wire saw and placed in the seed crystal slot of the crucible to induce the growth of specific preferential crystal planes, thereby increasing the orientation of the (012) crystal plane and improving the impurity separation efficiency.

[0050] Example 3

[0051] The present invention provides a multi-scale research method for improving the impurity separation efficiency in ultra-high purity metal systems. The difference from Example 1 is that the melting rate is changed to 75 and 100 mm h -1 , including the following steps:

[0052] S1. Prepare tellurium crystals by zone melting and analyze their purity and crystal orientation.

[0053] The 5N grade tellurium raw material was placed in a quartz boat (550 mm × 50 mm × 50 mm), and then loaded into the quartz tube of the partition purification device. High-purity argon gas was continuously introduced to purge the air in the quartz tube. As the heating coil was running, the melting area moved from the head to the tail of the sample. The melting rates were 75 and 100 mm h -1 The purity of the sample was determined by inductively coupled plasma mass spectrometry, and the crystal orientations of the sample were (101) and (012) by X-ray diffraction analysis.

[0054] S2. Analyze the interface structure and grain competition-driven orientation changes during solidification using phase-field simulation.

[0055] Phase-field simulation was conducted using a tellurium system containing tin and bismuth impurities to simulate the competitive growth of dendrites on the (001), (011), (012) and (101) crystal planes as the melting rate varied. It was found that at high melting rates, the (012) crystal plane showed preferential growth.

[0056] S3. Density functional theory is used to calculate and analyze the adsorption energy of impurity atoms on different crystal planes at the solid-liquid interface to obtain the structure-activity relationship between crystal plane orientation and impurity separation efficiency;

[0057] Density functional theory was used to calculate and analyze the adsorption energies of impurity atoms at the solid-liquid interface on the (101) and (012) crystal planes. It was found that the adsorption energy of the (012) crystal plane on all impurity atoms in the system was higher than that on the (101) crystal plane, which means that impurity atoms are more easily separated from the (012) crystal plane to the liquid phase, which is beneficial to improving the impurity separation efficiency.

[0058] S4. The crystal plane and preferred orientation degree of tellurium crystals are regulated by the Bridgman method.

[0059] Tellurium crystal growth is carried out in a Bridgman crystal growth furnace. The tellurium-containing growth crucible is evacuated to a vacuum degree of 4×10 -5 Pa, and enclose the growth crucible with hydroxide flame; adjust the heating zone to grow tellurium crystals, the growth temperature is 460℃, and the temperature gradient is 10℃cm -1 , the growth rate is 1 mm h -1 Tellurium crystals were cut along the (012) crystal plane using a diamond wire saw and placed in the seed crystal slot of the crucible to induce the growth of specific preferential crystal planes, thereby increasing the orientation of the (012) crystal plane and improving the impurity separation efficiency.

[0060] Depend on Figure 1 It can be seen that the impurity content of Na, Se, Ca, Pb, and Mg decreases with increasing melting rate. Correspondingly, the impurity removal rate also shows an upward trend. On the other hand, the content and impurity removal rate of impurity elements such as Ag, Ni, Fe, and Cr show a random trend with melting rate. Therefore, the morphological evolution of the solid-liquid interface may determine the different purification behaviors of the impurity elements.

[0061] Depend on Figure 2 It can be seen that with the increase of melting rate, the orientation of tellurium crystals gradually changes. -1 When the melting rate reaches 75 mm h -1 When the melting speed reaches 100 mm h -1 When the melting rate is 25 mm h, the sample shows obvious (012) preferred orientation. The ratio of the main peak intensity to the secondary peak intensity is defined as the index of the degree of preferred orientation. Specifically, when the melting rate is 25 mm h -1 When I (104) / I (101) The ratio is 3.94, while at 100mm h -1 When I (012) / I (101) The ratio rose to 9.52, indicating that the degree of preferential orientation has been strengthened.

[0062] Depend on Figure 3 It can be seen that at 100mm h -1 The tellurium samples prepared at the melting rate have high crystallinity, defect-free structure, and show obvious (012) crystal plane orientation.

[0063] Depend on Figure 4 It can be seen that at 25mm h -1At a low melting rate of 100 mm h, tellurium exhibits large irregular grains in both the Y and X directions, accompanied by small subgrains. As the melting rate increases, the grain orientation becomes regular. -1 Uniformly oriented columnar grains are formed. At the same time, the size of the grains also tends to decrease. Therefore, with the increase of the melting rate, the irregular grains gradually transition to columnar grains, and preferentially oriented columnar grains are formed at high melting rates.

[0064] Depend on Figure 5 It can be seen that at lower melting rates, the (012) dendrites grow faster than the (011) dendrites. As the melting rate increases, the (012) dendrites begin to lag behind the (011) dendrites. As the melting rate increases further, the (012) dendrites once again take the lead in the growth competition, indicating that the (012) plane exhibits a preferred orientation for growth at high melting rates.

[0065] Depend on Figure 6 It can be seen that for all the impurity elements studied, the (012) crystal plane exhibits higher adsorption energies than the (104) crystal plane. Here, adsorption energy is defined as the systematic energy change of an impurity atom that migrates from the solid-liquid interface and is captured by the solid phase. Lower adsorption energy values ​​indicate a more favorable adsorption process and a less favorable impurity separation process. This means that the (012) crystal plane is more conducive to the separation of impurities into the liquid phase, facilitating their removal.

[0066] Depend on Figure 7 It can be seen that the Bridgman method was used to prepare tellurium samples with a higher degree of preferred orientation. Compared with the samples prepared by zone melting, the (012) and (104) plane orientation degrees increased from 9.52 and 3.96 to 20.57 and 19.72, respectively.

[0067] Depend on Figure 8 It can be seen that the impurity content of the (012) preferentially oriented sample prepared by the Bridgman method is significantly lower than that of the (104) oriented sample and the (012) oriented sample prepared by zone melting, and has a higher impurity removal rate, which means that the interface structure evolution has a significant influence on the deep separation of trace impurities.

[0068] The above description is only used to illustrate the technical solution of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, it should be understood by those skilled in the art that the technical solutions described in the embodiments may still be modified, or some or all of the technical features thereof may be replaced by equivalents. Any equivalent structural or equivalent process transformations made using the contents of the present invention's description and drawings, or directly or indirectly applied to other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A multi-scale research method for improving the impurity separation efficiency in ultra-high purity metal systems, characterized in that: The following steps are involved: S1. Prepare tellurium crystals by zone melting, analyze their purity and crystal orientation, and obtain experimental data. S2. Use phase field simulation to analyze the interface structure and grain competition-driven orientation changes during solidification to obtain macroscopic theoretical data; S3. Use density functional theory to calculate and analyze the adsorption energy of impurity atoms on different crystal planes at the solid-liquid interface, obtain the structure-activity relationship between crystal plane orientation and impurity separation efficiency, and obtain microscopic theoretical data; S4. The crystal plane and preferred orientation degree of the tellurium crystal are regulated by the Bridgman method to obtain an optimized solution.

2. The multi-scale research method for improving impurity separation efficiency in ultra-high purity metal systems according to claim 1, characterized in that: In step S1, the tellurium raw material is placed in a quartz boat and then loaded into the quartz tube of a zoned purification unit. High-purity inert gas is continuously introduced to purge the air in the quartz tube. As the heating coil operates, the melting zone moves from the head to the tail of the sample. The purification process is completed at a set melting rate, and the tellurium in the middle is collected. The purity of the tellurium crystals is analyzed by inductively coupled plasma mass spectrometry, and the crystal orientation is analyzed by X-ray diffraction. In step S2, a multiphase field model is used to simulate the interface evolution during the zone melting process. In step S3, calculations are performed using the DMOL3 software package based on density functional theory (DFT).

3. The multi-scale research method for improving impurity separation efficiency in ultra-high purity metal systems according to claim 2, characterized in that: The purity of the raw tellurium is 5-6N; the size of the quartz boat is 550mm×50mm×50mm; the inert gas is argon; the melting rates are 25, 50, 75, and 100 mm h -1 .

4. The multi-scale research method for improving impurity separation efficiency in ultra-high purity metal systems according to claim 1, characterized in that: In step S2, the phase field simulation uses a tellurium system containing impurity elements to simulate the competitive growth of dendrites on crystal planes such as (001), (011), (012), (104) and (101) as the melting rate changes.

5. The multi-scale research method for improving impurity separation efficiency in ultra-high purity metal systems according to claim 1, characterized in that: In step S3, the theoretical calculation is specifically the adsorption energy of impurity atoms at the solid-liquid interface of the (104), (101) and (012) crystal planes; the structure-activity relationship is that the lower the adsorption energy value, the lower the impurity separation efficiency.

6. The multi-scale research method for improving impurity separation efficiency in ultra-high purity metal systems according to claim 1, characterized in that: In step S4, the Bridgman method for controlling the crystal plane and preferred orientation of the tellurium crystal is as follows: the tellurium crystal is grown in a Bridgman crystal growth furnace. A tellurium-containing growth crucible is evacuated and encapsulated with a hydroxide flame, and the heated zone is adjusted to grow the tellurium crystal. The tellurium crystal is cut along a specific crystal plane using a diamond wire saw and placed in a seeding well in the crucible to induce growth of a specific preferred crystal plane.

7. The multi-scale research method for improving impurity separation efficiency in ultra-high purity metal systems according to claim 6, characterized in that: The vacuum degree of the crucible is 1×10 -5 -4×10 -5 The growth temperature of the Bridgman crystal growth furnace is 450-460 ℃, and the temperature gradient is 10-15 ℃ cm -1 , with a growth rate of 1-1.5 mm h -1 ; The specific crystal planes are (012), (104) and (101); the purpose of the regulation is to enhance the degree of preferential orientation of specific crystal planes.

8. The multi-scale research method for improving impurity separation efficiency in ultra-high purity metal systems according to claim 1, characterized in that: The metal samples in steps S1-S4 can be replaced by germanium, selenium, indium, antimony, rhenium, thallium, etc., and the method is universal.

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